kingers

Hi folks, I have a 2001 A8 2.8 V6 Quattro Sport (European).

It has a Lucas twin piston calliper (with 4 pads) on each side. However, they are quite different... the left hand one is as seen here -

audipages Front Brake Repair

However the right one is different, still a twin piston Lucas item that takes 4 pads.

Is this normal?

The reason I ask is that I got a set of pads that fits the right side but does not fit the left.....

Pad manufacturer got it wrong or have I got something truly funky going on?

tenspeed

The calipers should be a mirror image of each other. I have never heard of different calipers but it could be possible if some replaced a seized caliper with one from another year/model.

A more common problem is that the inner and outer pads are different and someone mounts both inners or outers on one caliper. Get to the other side and only one pad fits.

kingers

They are not a mirror image. And I have the pads where they should be.

To give a bit more detail - the left is as per the link above. This is a new caliper I just bought and was a like for like to what it replaced, it is the caliper that the parts shop specified to suit the car.

The right caliper uses pads that have springs on them for the outer pair. The calliper has size 24 bolts as per this thread - https://www.audiworld.com/forums/a8-...ipers-1750443/ I see that this guy has a 2001 A8L, I presume that is a V8??

Do the V8 Lucas calipers normally have a sixe 24 bolt head?

The left side has size 21mm and the different pad retaining springs that can be seen in the link. The sliders and general design is slightly different.

Perhaps it is like you say, an OEM Lucas caliper on the left and someone stuck the Lucas V8 caliper on the right......?

Piston sizes look the same and it certainly stops straight...

kingers

So here's a pic of what the right hand caliper looks like - Audi A8 D2 PF OS Right Front Brake Caliper | eBay

That came off a pre facelift 4.2 V8..... looks more like someone stuck one on my car ...

kingers

Although this is the mirror image of the right hand side caliper but its off a 2.8

Audi A8 D2 PF NS Left Front Brake Caliper | eBay

Jesus, Audi didn't half chop and change around the brakes on the models....

In fact the more I look at ebay, the more I can see that either of the callipers featured on facelift, pre facelift, V8's and V6's ..... can't seem to find a theme to why they on some cars and not on others...

kingers

Sorry for all the replys (can't figure out how to edit a post) - I've looked again and it seems the right hand caliper is a pre facelift Lucas item. I think there is mention somewhere in the service history of it getting a caliper in the past so I reckon they made the mistake of getting an early one, or that's all that was available to them in this part of the world.

Looks like I'm buying 2 sets of pads to do one axle ....

tenspeed

Think of it as buying pads for two brake jobs at the same time.

twentysevenlitres

My speculation would be the same as tenspeed's, that one of the calipers has been replaced at some point for some reason.

They shouldn't be different.
to get even braking left to right (critically important on the steering 'axle'), you need to have an identical clamping force. You'll only get this with mirror image or identical calipers and rotors and same brand pads.

If the pistons in the calipers have the same diameter (area), then they will exert the same physical force on the pad. However to exert the same force on the disc surface, the pads need to be the same physical size on each caliper. By the sounds of things yours are different.
If I were you, I would be looking for a pair to one or the other to even the setup out!

kingers

I hear you, piston sizes are the same, pads have pretty much same area, just slightly different shape, same disks and I'll have to get same pads.

If it affected the braking or pulled the car to one side I would change it but it's not making any difference ....

silverd2

I am NOT one to fix anything that ain't broken...BUT that, I would fix ...especially since it's the front brakes, which do all the work.

Even if I felt nothing in normal driving, just knowing it would leave me in constant "worry" about any upcoming full panic stop.